Carbohydrate Metabolism Pt. 1 Flashcards
What cells in our body undergo glycolysis?
All cells in our body undergo glycolsis
Can other monosaccharides enter glycolysis?
Yes. Fructose and galactose
Glucose is super important for the ________ and ________.
- RBCs
2. Brain
Why is glucose important for the brain?
In NON-STARVING conditions, glucose is the only fuel that the brain uses.
Where can we get our sources of glucose from?
- Monosaccharides like glucose, fructose and galactose
2. Disaccharides like [sucrose] and [lactose]
Sucrose, a disaccharide, can be broken down into ______ and _____ via
glucose
fructose
via sucrase
Lactate, a disaccharide, can be broken down into _____ and _____ via
glucose
galactose
via lactase
Gluconeogenesis in the liver called what?
De novo synthesis.
Why do RBC need glucose to survive?
Their only source of NRG is glucose. They do not have MT to make any other kinds of NRG.
When there is a defect in glycolysis, what cells suffer the most?
- RBCs and
2. Brain
Can glucose diffuse into cells?
No. It is polar. It needs the help of GLUT transporters
GLUT1
Location:
Affinity:
Km:
GLUT1 are found everwhere, but mainly the heart and the brain.
High affinity
Low Km
GLUT2
Location:
Affinity:
Km:
Liver
Low affinity
High Km
GLUT 3
Location:
Affinity:
Km:
Neuron
High affinity
Low Km
GLUT4
Location:
Affinity:
Km:
GLUT4
Location:
skeletal muscle
fat and
heart
TRICK: GLUT4 are special because they are insulin-dependent.
When glucose is high, insulin binds to receptors on a enzyme. Usually, GLUT4 receptors are stored in vesicles in the cell. So when insulin binds, this signals for GLUT4 receptors to be placed in the membrane.
Before we begin glycolysis: what is the strategy in glycolysis and the TCA cycle?
We want to HARNESS chemical NRG.
The more that carbon is reduced (gaining H and electron; losing O), the more NRG that it can have. Why? Because when Carbon is oxidized (gains an oxygen or loses H/electrons), NRG is released.
ATP can be formed by substrate-level phosphorylation from high energy compounds like ______ and ______
13BPG and
PEP
Oxidation
Gain O
Lose H/electrons
Reduction
Gain H/electrons
Lose O
What is SLP?
SLP is when we make ATP from ADP by transferring a phosphate.
What 2 intermediates in glycolysis undergo SLP?
- PGK [1,3 BPG–>3PG]
2. Pyruvate kinase
In glycolysis, in all steps that involve ATP, what cofactor is needed?
Mg2+
What in glycolysis generates the first high NRG intermediate?
GAP3DH creates NADH.
____ is the NRG money of the cell. Why?
NADH.
NADH stores NRG as 2 electrons, which can then be taken to the ETC
Catabolic pathways do what?
Catabolic pathways break down via
EXERGONIC, OXIDATIVE to make ATP
Anabolic pathways do what?
Anabolic pathways BUILD UP via
endergonic, reductive reactions.
What is the net yield of glycolysis?
4 energy molecules total:
- 2 ATP
- 2 NADH
Where does anaerobic glycolysis occur?
RBC and overworked muscle
What happens in anaerobic glycolysis?
Pyruvate–> lactate.
How can we remove lactic acid in overworked muscle or RBC when it is too much?
Cori cycle.
3 phases of glycolysis:
- Investment- need 2 ATPs
- Splitting
- Recoup- 2 ATP and 2 NADH
Investment phase important enzymes
- Hexokinase/glucokinase: Glu–>G6P
- F6P–> F16BP: PFK1
* main regulatory step
Why is it called the investment phase?
2 ATP are needed
In any step in glycolysis that involves ATP, we need what cofactor?
Mg2+
What is the main regulatory step of glycolysis?
PFK1.
Where is hexokinase located?
All cells
Where is glucokinase located?
Liver
Pancreatic B cells.